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/*
==============================================================================
JUCE demo code - use at your own risk!
==============================================================================
*/
class SpectrogramComponent : public AudioAppComponent,
private Timer
{
public:
SpectrogramComponent()
: forwardFFT (fftOrder, false),
spectrogramImage (Image::RGB, 512, 512, true),
fifoIndex (0),
nextFFTBlockReady (false)
{
setOpaque (true);
setAudioChannels (2, 0); // we want a couple of input channels but no outputs
startTimerHz (60);
setSize (700, 500);
}
~SpectrogramComponent()
{
shutdownAudio();
}
//==============================================================================
void prepareToPlay (int /*samplesPerBlockExpected*/, double /*newSampleRate*/) override
{
// (nothing to do here)
}
void releaseResources() override
{
// (nothing to do here)
}
void getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill) override
{
if (bufferToFill.buffer->getNumChannels() > 0)
{
const float* channelData = bufferToFill.buffer->getWritePointer (0, bufferToFill.startSample);
for (int i = 0; i < bufferToFill.numSamples; ++i)
pushNextSampleIntoFifo (channelData[i]);
}
}
//==============================================================================
void paint (Graphics& g) override
{
g.fillAll (Colours::black);
g.setOpacity (1.0f);
g.drawImage (spectrogramImage, getLocalBounds().toFloat());
}
void timerCallback() override
{
if (nextFFTBlockReady)
{
drawNextLineOfSpectrogram();
nextFFTBlockReady = false;
repaint();
}
}
void pushNextSampleIntoFifo (float sample) noexcept
{
// if the fifo contains enough data, set a flag to say
// that the next line should now be rendered..
if (fifoIndex == fftSize)
{
if (! nextFFTBlockReady)
{
zeromem (fftData, sizeof (fftData));
memcpy (fftData, fifo, sizeof (fifo));
nextFFTBlockReady = true;
}
fifoIndex = 0;
}
fifo[fifoIndex++] = sample;
}
void drawNextLineOfSpectrogram()
{
const int rightHandEdge = spectrogramImage.getWidth() - 1;
const int imageHeight = spectrogramImage.getHeight();
// first, shuffle our image leftwards by 1 pixel..
spectrogramImage.moveImageSection (0, 0, 1, 0, rightHandEdge, imageHeight);
// then render our FFT data..
forwardFFT.performFrequencyOnlyForwardTransform (fftData);
// find the range of values produced, so we can scale our rendering to
// show up the detail clearly
Range<float> maxLevel = FloatVectorOperations::findMinAndMax (fftData, fftSize / 2);
for (int y = 1; y < imageHeight; ++y)
{
const float skewedProportionY = 1.0f - std::exp (std::log (y / (float) imageHeight) * 0.2f);
const int fftDataIndex = jlimit (0, fftSize / 2, (int) (skewedProportionY * fftSize / 2));
const float level = jmap (fftData[fftDataIndex], 0.0f, maxLevel.getEnd(), 0.0f, 1.0f);
spectrogramImage.setPixelAt (rightHandEdge, y, Colour::fromHSV (level, 1.0f, level, 1.0f));
}
}
enum
{
fftOrder = 10,
fftSize = 1 << fftOrder
};
private:
FFT forwardFFT;
Image spectrogramImage;
float fifo [fftSize];
float fftData [2 * fftSize];
int fifoIndex;
bool nextFFTBlockReady;
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (SpectrogramComponent)
};
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